Silver halide color photographic materials are generally classified into color negative photographic materials and color reversal photographic materials. "Color negative photographic materials" refers to color photographic materials capable of forming negative images by applying thereto color negative processing after imagewise exposure, and "color reversal photographic materials" refers to color photographic material capable of forming positive images by applying thereto color reversal processing after imagewise exposure. Both the color negative photographic material and the color reversal photographic material have fundamental similar structures. That is, both of these color photographic materials are composed of a support having coated thereon combinations of at least three kinds of silver halide emulsions each having different color sensitivity (the color sensitivity is a property of being sensitive to one of three visible spectral regions, i.e., red, green, or blue), and three couplers, for forming cyan, magenta, and yellow dyes, respectively.
For forming images having proper color reproduction in a silver halide color photographic system, colored dyes having appropriate spectral sensitivity distributions and spectral absorption characteristics are applied for the silver halide color photographic material, and are particularly required to keep a proper balance in the gradation characteristics of plural color images and a proper balance in sensitivity.
It is preferred that the quality of images obtained using a color photographic material is determined by photographing various photographic subjects, but a method of evaluating the quality of color images by the form of a characteristic curve of each color photographic material, showing the image density as a function of an exposure amount, is usually employed as a practical and objective test in the field of the art. For example, it is described in Eiji Hozumi, Practice of Sensitometry, 1st edition, page 156, that gradation characteristic balance and sensitivity balance of a color image have a strong influence on the color reproducing characteristics and tone reproducing characteristics of the image of the color photographic material.
That is, with respect to the gradation characteristic balance between different color images, in general, there exist portions from a highlight portion having comparatively low density to a shadow portion having a comparatively high density in colors reproduced in a picture, and in a silver halide color photographic material having improper gradation characteristic balance, even when a proper color reproduction is obtained, for example, in a highlight portion, undesirable color reproduction is obtained in an intermediate portion or a shadow portion, or even when a proper color reproduction is obtained in an intermediate portion, undesirable color reproduction is obtained in a shadow portion or a highlight portion. Also, with respect to the sensitivity balance between different color images, it is important that the sensitivities of the color images are matched with a sensitivity set to obtain the optimum image. If even one of the color images is outside the optimum sensitivity condition, the color balance of the color images obtained differs from that of the real photographic subject, and hence unsatisfactory results are obtained.
As described above, the gradation characteristic balance and the sensitivity balance of different color images are very important characteristics in a color photographic material.
Now, color photographic materials are usually continuously processed by means of an automatic developing machine in a photographic laboratory, but since each photographic laboratory employs each processing condition for each automatic processor in the laboratory, it sometimes happens that even in the case of using the same kind of color photographic materials, a desired photographic performance (in particular, a desired gradation characteristic balance and a desired sensitivity balance among the above-described different color images) cannot be obtained by a photographic laboratory. This problems becomes serious in the case of performing high-temperature quick development processing for the purpose of reducing the costs and labor required for the photographic process.
As the result of extensive investigations on the cause of this problem, the present inventors have found that the difference in the extent of stirring for the developer of a color development in the case of a color negative development process or of a first development (black-and-white development) in the case of a color reversal development process causes a difference in the photographic performance according to the differences in the sort of an automatic processor employed in each photographic laboratory. The difference in the extent of stirring for a developer as noted above occurs in an ordinary photographic process according to the size of a developer tank, the nitrogen gas bubbling time and the place of forming nitrogen bubbles in the case of performing the stirring by bubbling of nitrogen gas, the number of photographic materials immersed in the developer, the difference in the type of the processor, e.g., a hanger type, a roll type, a roller transport type, etc., and the transporting speed of a photographic film to be processed.
It has further been found that when a so-called mono-dispersed silver halide emulsion is used for a silver halide photographic emulsion, the image quality is liable to be deteriorated by deviations in the stirring conditions, as described above, for the developer.
A mono-dispersed silver halide emulsion means a silver halide emulsion wherein more than 95% of the total silver halide grains, in grain number of weight, have grain sizes within .+-.40% of the mean grain size, and, because of the photographic characteristics of relatively high contrast, if the mono-dispersed silver halide emulsion is used for a low-sensitive silver halide emulsion layer which is selected from two or more split light-sensitive silver halide emulsion layers each having the same color sensitivity but having different sensitivity, the reproducibility of the highlight portion (e.g., the highlight portion of the printed image on a color photographic paper in the case of a color negative photographic material, or the highlight portion of images formed in a color reversal photographic material) of images is excellent as compared to the case of using a poly-dispersed silver halide photographic emulsion.
The reason why the influence of the deviation of the stirring condition for a developer becomes large in the case of using a mono-dispersed silver halide emulsion has not yet been fully clarified, but it is thought that since a mono-dispersed silver halide emulsion has high contrast gradation characteristics, as described above, when the sensitivity is fluctuate by the change of the stirring condition at development, the changing extent of the image density occurring with the dispersion is liable to become large and the change in visual tint of images is liable to become conspicuous.